1. Field of the Invention
The present invention relates generally to rewritable recording media, and more particularly, to an efficient management method of navigation information on a rewritable recording medium which are referred to when data on the recording medium are edited and reproduced or data are recorded to the recording medium.
2. Description of the Related Art
Optical discs have come into wide use since the advent of compact disc (CD) and the demand for optical discs is expected to grow steadily with popularization of digital versatile disc (DVD). Optical discs include read-only discs such as CD-ROM and DVD-ROM, write-once discs such as CD-R and DVD-R, and rewritable discs such as CD-RW and DVD-RAM. The specification of DVD-RTRW, which is standard writing/reading format of a rewritable disc, has not released yet and standardization for DVD-RTRW is in progress. As rewritable optical discs like DVD-RAM are of immensely large capacity, users may store a variety of data such as moving pictures, still pictures, audio data, and the like on a single recording medium. Each time a new data file is recorded on a rewritable recording medium, navigation information for locating the data file after the recording is created and recorded along with the data file on the recording medium. The recorded navigation information is referred to whenever the relevant data file is accessed.
Navigation information regarding all data files stored on a recording medium is contained in a navigation data table as shown in FIG. 1, which is recorded as a single data file on the recording medium. Accessing the recording medium entails loading the navigation data file into a memory, wherein the navigation data reside all the time. When recording a moving or still picture on the recording medium, the area in which the picture file will be recorded is determined with reference to the navigation information. Recording a picture file always accompanies creating management information regarding the recorded picture file and updating the navigation data file to include the newly created management information.
Navigation data pertaining to moving pictures comprise movie video object information (M_VOBI) and movie video object presentation order information (movie Cell Information or simply CI). Suppose that a moving picture file is composed of n movie video objects (M_VOBs), e.g., M_VOB#1.about.M_VOB#n as shown in FIG. 3. Since each M_VOB needs a M_VOBI and a CI, n M_VOBIs and n CIs are created in the same order that n M_VOBs are recorded. In FIG. 3, M_VOBI#1.about.M_VOBI#n correspond to M_VOB#1.about.M_VOB#n and C#3, . . . , C#k (shaded cells in the box labeled ORG_PGC) correspond to M_VOB#1.about.M_VOB#n. The created M_VOBIs and CIs are stored in the movie A/V file information table (M_AVFIT) and the original program chain information table (ORG_PGCIT) of the navigation data shown in FIG. 1, respectively.
On the other hand, navigation data pertaining to still pictures comprise still picture video object information (S_VOBI) and still picture video object presentation order information (still picture Cell Information or simply CI). Suppose that a still picture file is composed of n still picture video objects (S_VOBs) S_VOB#1.about.S_VOB#n as shown in FIG. 3. Since each S_VOB needs a S_VOBI and a CI, n S_VOBIs and n CIs are created in the same order that n S_VOBs are recorded. In FIG. 3, S_VOBI#1.about.S_VOBI#n correspond to S_VOB#1.about.S_VOB#n and C#1, C#2, C#4, . . . , C# (k-1) (not shaded Cells in the box labeled ORG_PGC) correspond to S_VOB#1.about.S_VOB#n. The created S_VOBIs and CIs are stored in the still picture A/V file information table (S_AVFIT) and the original program chain information table (ORG_PGCIT) of the navigation data shown in FIG. 1, respectively.
When the rewritable recording medium is accessed for reproduction, the navigation data file is read out from the recording medium and loaded into a memory. If reproduction of a moving picture (still picture) is requested, M_VOBIs (S_VOBIs) and CIs relevant to the requested moving picture file (still picture file) are read from the M_AVFIT (S_AVFIT) and ORG_PGCIT of the navigation data table, respectively. With reference to the M_VOBIs (S_VOBIs) and CIs, the requested moving picture file (still picture file) can be located from the recording medium and reproduced.
The navigation data file is used in the same manner when a moving or still picture files recorded on the recording medium is edited. If a user edits a play list of moving or still pictures to reproduce them in a preferred order, management data regarding the changed play list are created with reference to the navigation data loaded into the memory. The management data consist of a new series of CIs corresponding to the selected pictures, e.g., C#1'.about.C#m' of FIG. 3, which forms a user-defined PGC (UD_PGC) to be stored in the user-defined PGC information (UD_PGCI) of the UD_PGCIT shown in FIG. 1. UD_PGC#i is stored in UD_PGCI#i (i=1,2, . . . , n). If reproduction of the edited play list of the picture files is requested, the UD_PGC stored in the UD_PGCI corresponding to the requested play list is read from the UD_PGCIT of the navigation data in the memory. Then, the M_VOBIs and S_VOBIs corresponding to the CIs in the UD_PGC can be read from the M_AVFIT and S_AVFIT. For example, in FIG. 3, S_VOBI#2.about.S_VOBI#4, S_VOBI#7 .about.S_VOBI#8, . . . , M_VOBI#6 .about.M_VOBI#8 are read out. Finally, the VOBs linked to the play list can be read out and the play list can be reproduced in reference to the VOBIs and CIs.
In the navigation data configured as above, video manager information management table (VMGI_MAT) comprises, as shown in FIG. 2, a video manager identifier (VMG_ID) for representing a navigation data file; an address (RTRWI_EA) for specifying the end address of the navigation data table which is represented by a relative logical block number from the beginning of the table; an address (VGMI_EA) for specifying the end address of the video manager information (VGMI) which is represented by a relative byte number from the beginning of the VGMI; and a version number (VERN) of the rewritable recording medium.
As shown in FIG. 1, each information table has an address field which indicates the end address of the information table: M_AVFIT_EA in movie A/V file information table information (M_AVFITI) specifies the end of M_AVFIT, S_AVFIT_EA in still picture A/V file information table information (S_AVFITI) for S_AVFIT, ORG_PGCIT_EA in original PGC information table information (ORG_PGCITI) for ORG_PGCIT, UD_PGCI_EA in user-defined PGC information table information (UD_PGCITI) for UD_PGCIT, TXT_DT_MG_EA in text data information (TXTDTI) for text data manager (TXT_DT_MG), and MNFIT_EA in manufacturer's information table information (MNFINI) for manufacturer's information table (MNFIT).
For example, in order to access original PGC information (ORG_PGCI) of the navigation data of FIG. 1, first, the end address of VMGI, or VMGI_EA is read out from VMGI_MAT of VMGI. M_AVFIT is located in reference to the VMGI_EA because M_AVFIT is the next information table of VMGI. Then, M_AVFIT_EA is read out from M_AVFITI of M_AVFIT. In the same way, S_AVFIT_EA is obtained from S_AVFINI of S_AVFIT in reference to the M_AV_FIT_EA, and then the ORG_PGCI is accessed by referencing the next address of the S_AVFIT_EA.
Therefore, the navigation data file structure, where the end addresses for the information tables such as VMGI_EA, M_AVFIT_EA, S_AVFIT_EA, ORG_PGCIT_EA, UD_PGCIT_EA, TXT_DT_MG_EA, and MNFIT_EA are used for locating, must be loaded on a memory in such a way that the information tables such as VMGI, M_AVFIT, S_AVFIT, ORG_PGCIT, UD_PGCIT, TXT_DT_MG, and MNFIT are arranged contiguously in order to access each information table appropriately.
In addition, when some data, for example, moving pictures are written to the rewritable recording medium, M_VOBI#i and C#i are generated corresponding to the M_VOB#i to be recorded newly and are then written to M_AVFIT and ORG_PGCIT, respectively. Since the information tables of the navigation data are arranged on the memory contiguously, as shown in FIG. 4A, writing the generated M_VOBI#i into M_AVFIT requires that information tables after the M_AVFIT be moved back by the size of the M_VOBI#i (shaded area in M_AVFIT in FIG. 4B), as shown in FIG. 4B. After writing the M_VOBI#i is completed, the end addresses of the M_AVFIT and information tables thereafter are updated. Likewise, in order to write the C#i into ORG_PGCIT, it is required that information tables positioned after the ORG_PGCIT are moved back by the size of the C#i (shaded area in ORG_PGCIT in FIG. 4B). Writing the C#i into ORG_PGCIT is followed by updating the end addresses of ORG_PGCIT and information tables thereafter. In other words, in the prior navigation data file structure, it takes more reading-and-writing cycle of information tables on the memory to write management information, which are generated when data are written to a rewritable recording medium, to the navigation data. As a result, updating management data requires more time for memory operation.
Because, in the prior navigation data file structure, access to the information tables in the navigation data such as M_AVFIT, S_AVFIT, ORG_PGCIT, UD_PGCIT, TXT_DT_MG, and MNFIT is made through a series of referencing the end addresses of preceding information tables, the access time is rather long and thereby it may be a burden to real-time operation for writing/reproducing data to/from the rewritable recording medium.